Monday, 2 January 2012

I quoted Professor Gordon in my last blog (Structures, or Why things don't fall down), and would like to
do so again:

“The English railways were built straight and level across
the rolling English landscape by the lavish use of cuttings and embankments and
splendid viaducts of masonry and ironwork. All this engineering luxury depended
upon supplies of capital and labour, both of which were plentiful in Victorian
England. Conditions in America were totally different. The distances were
enormous; capital was scarce; the wages, even of unskilled men, were high. In
the Land of the Free, where every man was an amateur, skilled craftsman of the
European type scarcely existed. Iron was expensive, but there was unlimited
cheap timber. […]

“The railroads were pushed westwards as fast as they could
be built and with a minimum of expensive cuttings and embankments. When
conditions were suitable, the valleys were bridged by means of enormous timber
trestle viaducts.”

The American railways could be built quickly and
cheaply because wooden trestle bridges were used very
extensively to save the cost of earthworks (c. 1875)

“These will always be associated, in tradition, with the
American railways; a fair number of them survive today. Once they had been
constructed, the American railways were vastly profitable – the Central Pacific
Railroad is said to have paid dividends of 60 per cent – and they were soon
able to convert many of their precarious trestle bridges to solid earth
embankments by tipping soil from specially constructed trains until the whole
wooden structure was encased in earth and could be left to rot away.”

To begin with then, what the Americans did was make the
minimum change for the maximum effect; they did as much as possible at least
cost first; they got their rail network to function,
which means to say, they got the thing up and running. It is true that U.S.
railroad engineers were prepared to take more risks with other people’s lives
than their British counterparts, as evidenced by their reliance on ‘primitive
bridges’, but as Rev. Samuel Manning noted at the time, “it is said that few
accidents have happened from their use.” Significantly, the cost per mile of
American railways was one fifth of that of English lines.

As soon as they were able, the Americans improved the standard
of their rail network, for although the wooden trestle bridges were objectively
or statistically safe, they were not subjectively safe. Samuel Manning again:

“The road is carried across valleys hundreds of feet in
depth on rude trestle bridges, which creak and groan beneath the weight of the
train. Anything apparently more insecure than these structures can hardly be
found elsewhere, and I always drew a long breath of relief as I found myself
safely on the other side. It is a fearful thing to look out of the carriage
windows into the dizzy depth below, and feel that if the frail fabric were to
collapse, as it seemed on the point of doing, we should all be dashed to pieces
with no possibility of escape.”

The Americans began by developing their rail network to a
minimum (or ‘rude’, or ‘primitive’, or ‘crap’) level of functioning. They did
so by making the best use of the locally available resources. To all but the more
hardened souls, riding on it was ‘a fearful thing’. Fortunately, not many of
the passengers lost their lives during these early years, but as more people
used the network, so more money became available to improve it.

The Americans understood very well that a pursuit of
perfection can lead to paralysis. Oftentimes it is most appropriate to make
the best of the circumstances as you find them. Obviously the Victorian
approach was ‘better’, but as Professor Gordon points out: “British engineers
were certainly not unduly cautious men; nowadays we should consider them rash.”